An online EMF prediction device and method for hearth wall thickness at the end of blast furnace service

Abstract

This invention belongs to the field of blast furnace lining safety monitoring technology, and particularly relates to an online EMF (Electromagnetic Prediction) device and method for predicting hearth wall thickness at the end of blast furnace service. The device includes a dedicated iron pipe fixed at the grouting hole in the furnace shell, a sleeve extending through the furnace shell into the carbon bricks, and carbon ramming material filling the space between the sleeve and the carbon bricks. Multiple EMF probes with different insertion depths are arranged inside the sleeve and fixed with nuts and caps, which are connected to the dedicated iron pipe. In use, the existing grouting hole is first cleaned, the dedicated iron pipe is welded, the sleeve is inserted and ensured to fit tightly against the carbon bricks, the EMF probes are installed, and the spacer is filled and fixed with ramming material. Finally, the hearth wall thickness is calculated using electromotive force, material thermal conductivity, Seebeck coefficient, and heat flux density. This invention requires no drilling, can be installed without interrupting production, offers high safety, is securely installed, and has reliable sealing, enabling high-precision online continuous monitoring of hearth wall thickness.

Description

Technical Field

[0001] This invention belongs to the field of blast furnace lining safety monitoring technology, and particularly relates to an online prediction device and method for hearth wall thickness EMF at the end of blast furnace service. Background Technology

[0002] The blast furnace hearth is the core structure of ironmaking production, and its service condition directly affects the safe production and economic benefits of the blast furnace. During long-term operation, the hearth lining is subjected to scouring by molten iron, thermal load, and chemical erosion. Especially towards the end of the furnace's service life, the thickness of the remaining furnace wall continues to decrease, approaching the safety threshold. Once a burn-through occurs, it will cause serious accidents such as high-temperature molten iron leakage, explosion, fire, and toxic gas leakage, resulting in casualties, equipment damage, and production stoppage. At the same time, the cost of emergency repairs for major accidents is high, and it can also lead to the premature end of the blast furnace's service life, reducing the total life cycle capacity and return on investment.

[0003] Current traditional technologies for monitoring furnace hearth wall thickness have significant drawbacks. Thermocouple temperature measurement models typically have inversion errors between ±50mm and ±150mm, and their accuracy is greatly affected by the density of measurement points and model simplification. Ultrasonic thickness measurement is affected by high temperatures, noise, and signal attenuation at the site, increasing the effective measurement error to over ±35mm to ±50mm, and it is difficult to achieve stable and continuous online measurement. Indirect methods such as furnace skin temperature measurement, infrared thermography, and stress measurement have even larger errors, generally exceeding ±100mm. They also have slow response times and cannot directly invert the thickness, making it difficult to accurately capture the millimeter-level evolution of furnace lining erosion.

[0004] EMF measurement technology has become a new direction for hearth wall thickness monitoring due to its advantages of fast response, high sensitivity and direct reflection of the intrinsic properties of materials. However, traditional EMF monitoring schemes require direct drilling into the furnace shell. The erosion status is unclear at the end of the furnace service, and the drilling depth is difficult to control accurately. There is a major safety risk of molten iron leakage caused by penetrating the thin furnace lining. In addition, the existing installation method has problems such as easy probe loosening, poor sealing, long signal transmission path and insufficient monitoring accuracy.

[0005] Therefore, there is an urgent need for an online EMF prediction method for the hearth wall thickness at the end of the blast furnace service. Summary of the Invention

[0006] The purpose of this invention is to provide an online EMF prediction device and method for hearth wall thickness at the end of blast furnace service, so as to solve the above-mentioned problems.

[0007] To achieve the above objectives, the present invention provides the following solution: An online EMF prediction device for hearth wall thickness at the end of blast furnace service includes: Special iron pipes are fixed at the grouting holes of the blast furnace shell at the end of the furnace service period; The sleeve passes through the furnace shell via the special iron pipe and extends into the carbon bricks located inside the furnace shell; Carbon ramming material is filled into the gap between the sleeve and the carbon brick. It also includes multiple EMF probes with different insertion depths. The EMF probes are inserted into the carbon ramming material inside the sleeve. The EMF probes are fixedly connected with nuts and caps, which are fixed to the special iron pipe.

[0008] Optionally, multiple EMF probes are arranged at equal intervals around the circumference.

[0009] Optionally, the sleeve is made of a high-temperature resistant material.

[0010] Optionally, the end of the special iron pipe is provided with an external thread, and the nut cap is fitted onto the outside of the end of the special iron pipe and fixed by the thread.

[0011] A method for using an online EMF (Earning Factor Prediction) device for predicting hearth wall thickness at the end of a blast furnace service life, comprising the following steps: Select the grouting hole on the furnace shell and remove the original filling material from the grouting hole and clean it until the hole wall is solid and clean; The special iron pipe is welded and fixed to the furnace shell, and the special iron pipe is coaxial with the grouting hole; Insert the sleeve into the grouting hole until the end of the sleeve contacts the wall of the carbon brick; Determine the insertion depth of each EMF probe, insert the EMF probe into the sleeve, and fill the sleeve and the gap between the sleeve and the carbon brick with carbon ramming material to fix the sleeve and the carbon brick and the EMF probe to the sleeve. The EMF probe is fixed to the nut cap, and the nut cap is fixed to the special iron pipe; After the EMF probe is installed, the furnace hearth wall thickness is calculated using the following formula: ; Where E(δ) is the electromotive force measured in the hearth, δ is the hearth wall thickness, S is the Seebeck coefficient, q is the heat flux density, and λ is the thermal conductivity of the material.

[0012] Compared with the prior art, the present invention has the following advantages and technical effects: This device utilizes existing grouting holes in the blast furnace shell for online installation of EMF probes, eliminating the need for re-drilling the shell at the end of the furnace's service life. This fundamentally avoids the safety risks of molten iron leakage caused by lining penetration and allows for construction to be completed without interrupting production. Employing multi-depth, circumferentially uniformly arranged EMF probes for signal acquisition, it comprehensively and stably acquires the internal potential signal of the hearth, improving the accuracy and reliability of wall thickness monitoring. A flexible inner rod structure between the sleeve and carbon bricks ensures a self-checking fit, guaranteeing accurate probe placement and tight contact, effectively improving signal transmission stability. The entire device uses threaded connections and fastening structures combined with ramming material for secure fixing, resulting in a firm installation and excellent sealing. It can withstand the harsh conditions of high temperatures and vibrations at the blast furnace site and is not prone to loosening over long-term use. The device directly calculates the hearth wall thickness using electromotive force, eliminating the need for temperature measurements, reducing environmental interference, and offering high calculation accuracy and fast response speed. It can reflect changes in hearth wall thickness in real time, providing stable and reliable data support for safe blast furnace operation at the end of its service life, early warning of burn-through risks, and extending service life. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the EMF probe of the present invention installed on the nut cap; Figure 3 This is a schematic diagram of the nut cap structure of the present invention; Figure 4 This is a schematic diagram of the sleeve structure of the present invention; The components include: 1. EMF probe; 2. Nut cap; 3. Special iron pipe; 4. Furnace shell; 5. Nut; 6. Sleeve; 7. Carbon ramming mix; 8. Weld joint; 9. Carbon brick; 10. Copper hoop; 11. Inner rod; 12. Spring. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] Reference Figures 1 to 4 This invention discloses an online EMF prediction device for hearth wall thickness at the end of blast furnace service, comprising: Special iron pipe 3 is fixed at the grouting hole of the furnace shell 4 at the end of the furnace service period; The sleeve 6 passes through the furnace shell 4 via a special iron pipe 3 and extends into the carbon brick 9 located inside the furnace shell 4; Carbon ramming material 7 is filled into the gap between the sleeve 6 and the carbon brick 9. It also includes multiple EMF probes 1 with different insertion depths. The EMF probe 1 is inserted into the carbon ramming material 7 inside the sleeve 6. The EMF probe 1 is fixedly connected with a nut cap 2, which is fixed to a special iron pipe 3.

[0017] This device is fixed to the grouting hole of the furnace shell 4 with a special iron pipe 3. The sleeve 6 extends into the carbon brick 9 through the special iron pipe 3. The sleeve 6 and the gap between it and the carbon brick 9 are filled with carbon ramming material 7. Multiple EMF probes 1 with different insertion depths are inserted into the carbon ramming material 7 in the sleeve 6. The EMF probes 1 are fixed with nuts and caps 2. Nuts and caps 2 are fixed with special iron pipe 3. The whole device forms a stable installation structure, which can realize online EMF monitoring of the hearth wall thickness at the end of the furnace service without secondary drilling, ensuring installation safety.

[0018] As an optional implementation, the end of the EMF probe 1 away from the carbon brick 9 is fixed to the nut cap 2 by a copper hoop 10 and a nut 5.

[0019] The end of the EMF probe 1 furthest from the carbon brick 9 is fixed to the nut cap 2 by a copper hoop 10 and a nut 5. The copper hoop 10 tightens and the nut 5 locks in place, making the connection between the EMF probe 1 and the nut cap 2 more secure, preventing loosening during use and ensuring stable monitoring signals.

[0020] As an optional implementation, multiple EMF probes are arranged at equal intervals around the circumference.

[0021] Multiple EMF probes are arranged at equal intervals around the perimeter, allowing the probes to collect signals from different directions, improving the comprehensiveness and accuracy of wall thickness monitoring and reducing measurement deviations.

[0022] As an optional implementation, the inner wall of the sleeve 6 is elastically slidably fitted with multiple circumferentially spaced inner rods 11, and a mark is set at the end of the inner rod 11 away from the carbon brick 9; The inner rod 11 and the sleeve 6 are elastically engaged by the spring 12; Before the sleeve 6 is inserted into the special iron pipe 3, the spring 12 causes the inner rod 11 to extend out of the sleeve 6 near the end of the carbon brick 9. After the sleeve 6 is inserted into the special iron pipe 3, one end of the inner rod 11 first contacts the side wall of the carbon brick 9, and then the sleeve 6 continues to be inserted until the end contacts the side wall of the carbon brick 9. At this time, the spring 12 is compressed and the mark on the other end of the inner rod 11 extends out of the inner wall of the sleeve 6.

[0023] The inner wall of the sleeve 6 has multiple circumferentially spaced inner rods 11 that slide elastically. The inner rods 11 are marked and elastically engage with the sleeve 6 through springs 12. Before insertion, one end of the inner rod 11 extends out. After insertion, it contacts the carbon brick 9 and compresses the spring 12 to extend the mark. This allows for a direct visual judgment of whether the sleeve 6 and the carbon brick 9 are tightly fitted, ensuring proper installation.

[0024] As an optional implementation, sleeve 6 is made of a high-temperature resistant material.

[0025] The sleeve 6 is made of high-temperature resistant material, which can adapt to the high-temperature working conditions of the blast furnace hearth, avoid sleeve deformation and damage, and ensure long-term stable use of the equipment.

[0026] As an alternative implementation, the inner rod 11 is provided in three parts.

[0027] The three inner rods 11 are evenly distributed around the circumference, which can stably support and accurately detect the fit between the sleeve 6 and the carbon brick 9, making the judgment more reliable.

[0028] As an optional implementation, the end of the special iron pipe 3 is threaded externally, and the nut cap 2 is fitted onto the outside of the end of the special iron pipe 3 and fixed by the thread.

[0029] The special iron pipe 3 has external threads at its end. Nut cap 2 is fitted on the outside of the end of the special iron pipe 3 and fixed by threads. The threaded connection is easy to install and disassemble, has good sealing performance, prevents gas leakage, and ensures the overall structure is stable.

[0030] A method for using an online EMF (Earning Factor Prediction) device for predicting hearth wall thickness at the end of a blast furnace service life, comprising the following steps: Select the grouting hole on the furnace shell 4 and remove the original filling material from the grouting hole and clean it until the hole wall is firm and clean; The special iron pipe 3 is welded and fixed to the furnace shell 4, and the special iron pipe 3 is coaxial with the grouting hole. Insert the sleeve 6 into the grouting hole until the end of the sleeve 6 contacts the wall of the carbon brick 9. Determine the insertion depth of each EMF probe 1, insert the EMF probe 1 into the sleeve 6, and fill the gap between the sleeve 6 and the carbon brick 9 with carbon ramming material 7 to fix the sleeve 6 and the carbon brick 9, and fix the EMF probe 1 and the sleeve 6. Fix the EMF probe 1 to the nut cap 2, and fix the nut cap 2 to the special iron pipe 3; After EMF probe 1 is installed, the furnace hearth wall thickness is calculated using the following formula: ; Where Eδ is the electromotive force measured in the furnace hearth, δ is the furnace hearth wall thickness, S is the Seebeck coefficient, q is the heat flux density, and λ is the thermal conductivity of the material.

[0031] First, clean the grouting holes of the furnace shell 4, weld the special iron pipe 3 and insert it into the sleeve 6 until it contacts the carbon brick 9. After determining the insertion depth of the EMF probe 1, fill it with carbon ramming material 7 to fix it. Then fix the EMF probe 1 with the nut cap 2 and the special iron pipe 3. Finally, calculate the hearth wall thickness by using electromotive force, thermal conductivity, Seebeck coefficient and heat flux density. This achieves safe installation and high-precision online wall thickness prediction at the end of the furnace service without stopping production. The operation process is clear and the measurement error is small.

[0032] In practice, the grouting hole is first professionally cleaned to remove the original filler and clean it until the hole wall is solid and clean. Then, a special iron pipe 3 with external threads is welded onto the furnace shell 4 at the hole opening.

[0033] Insert a compacted sleeve 6 into the grouting hole. The inner end of the sleeve 6 is in close contact with the carbon brick 9 to be measured, and the outer end of the sleeve 6 has a hole for installing the EMF probe 1 for fixing the EMF probe 1. The EMF probe 1 is placed inside the sleeve 6 and the entire sleeve 6 containing the EMF probe 1 is inserted into the grouting hole on the carbon brick 9. After determining the test depth of EMF probe 1 inserted into carbon brick 9, the other end of EMF probe 1 is tightened onto nut cap 2 of special iron pipe 3 using a fastening device. Tighten the nut cap 2 of the special iron pipe 3 through the external thread of the special iron pipe 3, and pour carbon ramming material 7 into the sleeve 6 to fix the EMF probe 1.

[0034] Furthermore, the grouting holes on the furnace shell 4 and carbon brick 9 are the welding points 8. A special iron pipe 3 is welded at the welding point 8. It is necessary to ensure that the inner diameter of the special iron pipe 3 is consistent with the size of the grouting holes on the furnace shell 4 and carbon brick 9, and that the sleeve 6 can be inserted smoothly. Furthermore, the sleeve 6 is made of high-temperature resistant material and is filled with carbon ramming material 7. The carbon ramming material 7 needs to fill the sleeve 6 completely and be rammed and compacted. Furthermore, the sleeve 6 has a hole for installing the EMF probe 1 at the outer end. It is necessary to determine the insertion depth of the EMF probe 1. When inserting the EMF probe 1, it is necessary to ensure that the front end of the probe is completely in contact with the carbon ramming material 7 inside the sleeve 6, and to ensure that the EMF probe 1 does not loosen after insertion.

[0035] Furthermore, three holes are made at 120° symmetrical positions around the center on the sleeve wall, each containing three inner rods with springs fitted on them. When the inner end of the sleeve is pressed tightly against the wall of the carbon brick 9, the inner rods are pushed outwards. When they are close to the wall, the outer end of the inner rods shows a locked mark. If they loosen, the inner rods are retracted by the springs, and the locked mark returns to the hole.

[0036] Furthermore, the entire sleeve equipped with the probe is inserted into the grouting hole on the carbon brick 9, including: the outer diameter of the sleeve is consistent with the inner diameter of the iron pipe, the furnace shell 4 and the grouting hole of the carbon brick 9, the inner end of the sleeve 6 is tightly attached to the carbon brick 9 to be measured, and the inner diameter of the insertion hole of the EMF probe 1 at the outer end is consistent with the outer diameter of the EMF probe 1, the insertion depth of the EMF probe 1 into the sleeve is determined, and the EMF probe 1 is fixed on the sleeve 6 without loosening. Furthermore, the nut cap 2 of the special iron pipe 3 has an internal thread that matches the external thread of the special iron pipe 3. Before tightening, the method also includes: determining the depth of the sleeve 6 inserted into the carbon brick 9, determining the depth of the EMF probe 1 inserted into the side wall of the furnace hearth, filling the remaining gaps in the grouting holes of the special iron pipe 3, the furnace shell 4 and the carbon brick 9 with carbon ramming material 7, and tightening the fastening device of the EMF probe 1 on the nut cap 2 of the special iron pipe 3. Furthermore, the fastening device includes: nut 5 and copper hoop 10.

[0037] Furthermore, the online installation method for the EMF probe 1 on the blast furnace hearth sidewall calculates the hearth wall thickness using the following formula: ; Where Eδ is the electromotive force measured in the furnace hearth, δ is the furnace hearth wall thickness, S is the Seebeck coefficient considered a constant, q is the heat flux density, and λ is the thermal conductivity of the material. When the material parameters S and λ are known, and the heat flux density q can be measured using a heat flux meter, the wall thickness δ can be directly calculated from the electromotive force E without measuring the temperature.

[0038] With the above settings, welding a special iron pipe 3 onto the grouting hole of the furnace shell 4 can provide error redundancy for the insertion and installation of the EMF probe 1, and the nut cap 2 provides a more convenient fastening method; the EMF probe 1, nut cap 2, fastening device and sleeve 6 are integrated into one unit, which are tightly installed together, not easy to loosen, easy to install, and have small testing errors; the fastening device of the nut cap 2 and the EMF probe 1 can adjust the insertion depth of the EMF probe 1 relative to the furnace shell 4, ensuring that the sleeve 6 is in close contact with the carbon brick 9 wall.

[0039] The calculation formula for furnace hearth wall thickness of the present invention has an error range of <5%, which is better than the traditional thermocouple formula for calculating furnace hearth wall thickness.

[0040] Application Example 1: Step 1: Select the existing grouting holes in the furnace hearth as the installation channel for the EMF monitoring points.

[0041] During implementation, the grouting hole was first professionally cleaned to remove the original filler and clean it until the hole wall was solid and clean. Then, a special iron pipe 3 with external threads was welded onto the furnace shell 4 at the hole opening.

[0042] Specifically, the grouting holes on the furnace shell 4 and carbon bricks 9 have a diameter of φ32mm-φ34.5mm, preferably 34mm. The special iron pipe 3 has an outer diameter of φ42mm, an inner diameter of φ43mm, and a length of 100mm.

[0043] Specifically, the special iron pipe 3 is welded to the grouting hole of the furnace shell 4, and is centered on the grouting hole of the furnace shell 4 and the carbon brick 9. The weld 8 is required to ensure airtightness to prevent gas leakage during production.

[0044] Specifically, the holes inside the special iron pipe 3, the furnace shell 4, and the carbon brick 9 need to be cleaned with a drill to facilitate the insertion of the sleeve 6 later.

[0045] Specifically, the hole depth is the sum of the furnace shell thickness 4 and the drilling depth of the carbon brick 9, and in this embodiment, it is preferably 270mm.

[0046] Step 2: Insert the compacted sleeve 6 into the grouting hole. The inner end of the sleeve is in close contact with the wall of the carbon brick 9 to be measured, and the outer end of the sleeve has a hole for installing the EMF probe 1 for fixing the EMF probe 1.

[0047] Specifically, the outer diameter of sleeve 6 is φ33mm and the length is 370mm.

[0048] Specifically, the inside of the sleeve 6 is filled with carbon ramming material 7 and compacted with a force of 200N.

[0049] Specifically, there are three holes symmetrically arranged at 120° intervals on the wall of the sleeve 6, each containing three inner rods 11. Springs 12 are fitted onto the inner rods 11. When the inner end of the sleeve 6 is pressed tightly against the wall of the carbon brick 9, the inner rods 11 are pushed outward. When they are close to the wall, the outer end of the inner rods shows a locked mark. If they loosen, the inner rods 11 are retracted by the action of the springs 12, and the locked mark is returned to the hole.

[0050] Specifically, the sleeve 6 has three EMF probe 1 holes of different depths at its outer end. The three holes are evenly distributed with a rotation angle of 120° based on the center of the sleeve. The three holes are 20mm away from the center of the sleeve, with a diameter of φ5mm and depths of 370mm, 280mm and 190mm respectively.

[0051] Step 3: Insert the EMF probe 1 into the fastening device, assemble the EMF probe 1 and the fastening device onto the nut cap 2, then place the EMF probe 1 inside the sleeve 6 and insert the entire sleeve containing the probe into the grouting hole on the carbon brick 9.

[0052] Specifically, the three EMF probes 1 have a diameter of φ5mm and lengths of 420mm, 330mm and 240mm respectively. They are inserted into the three holes from deep to shallow at the outer end of the sleeve 6 in descending order of length, and are locked in place without loosening.

[0053] Step 4: Tighten the nut cap 2 of the special iron pipe 3 through the external thread of the iron pipe, and pour ramming material into the groove of the carbon brick 9 to fix the EMF probe 1 and the sleeve 6.

[0054] Specifically, carbon ramming material is filled into the gap between the special iron pipe 3, carbon brick 9 and the sleeve 6 to ensure that the sleeve does not loosen.

[0055] Specifically, the nut cap 2 has a diameter of φ60mm. Screw the nut cap onto the special iron pipe 3 through the thread and tighten it to ensure that it is not loose.

[0056] Step 5: After determining the test depth of EMF probe 1 inserted into carbon brick 9, the other end of EMF probe 1 is tightened onto the nut cap 2 of the iron pipe using a fastening device. Specifically, the fastening device includes: nut 5 and copper hoop 10. The EMF probe 1 is inserted into the nut and copper hoop in sequence.

[0057] Specifically, by tightening the nuts 5, the copper clamps 10 are locked in place at the designated positions of the three EMF probes 1, which ensures that the EMF probes 1 are secured to the nuts and caps at the required depths, specifically at 370mm, 280mm, and 190mm of the EMF probes 1.

[0058] The online installation method for the EMF probe 1 on the blast furnace hearth sidewall involves calculating the hearth wall thickness using the following formula: Where Eδ is the electromotive force measured in the furnace hearth, δ is the furnace hearth wall thickness, S is the Seebeck coefficient (considered a constant), q is the heat flux density, and λ is the thermal conductivity of the material. When the material parameters S and λ are known, and the heat flux density q can be measured using a heat flux meter, the wall thickness δ can be directly calculated from the electromotive force E without temperature measurement. The error range of the calculation result using this formula for furnace hearth wall thickness is <5%, which is better than the error range of the traditional thermocouple formula for calculating furnace hearth wall thickness.

[0059] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0060] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A device for on-line prediction of the hearth wall thickness EMF at the end of the campaign of a blast furnace, characterized in that, include: A special iron pipe (3) is fixed at the grouting hole of the furnace shell (4) of the blast furnace at the end of its service life; The sleeve (6) passes through the furnace shell (4) through the special iron pipe (3) and extends into the carbon brick (9) located inside the furnace shell (4); Carbon ramming material (7) is filled in the gap between the sleeve (6) and the carbon brick (9). It also includes multiple EMF probes (1) with different insertion depths. The EMF probes (1) are inserted into the carbon ramming material (7) inside the sleeve (6). The EMF probes (1) are fixedly connected to a nut cap (2), and the nut cap (2) is fixed to the special iron pipe (3).

2. The online EMF prediction device for hearth wall thickness at the end of blast furnace service according to claim 1, characterized in that, The end of the EMF probe (1) away from the carbon brick (9) is fixed to the nut cap (2) by a copper hoop (10) and a nut (5).

3. The online EMF prediction device for hearth wall thickness at the end of blast furnace service according to claim 1, characterized in that, Multiple EMF probes (1) are arranged at equal intervals around the circumference.

4. A device for online prediction of hearth wall thickness EMF at the end of blast furnace service according to claim 1, characterized in that, The inner wall of the sleeve (6) is elastically slidably fitted with multiple circumferentially spaced inner rods (11), and a mark is set at the end of the inner rod (11) away from the carbon brick (9); The inner rod (11) and the sleeve (6) are elastically engaged by a spring (12); Before the sleeve (6) is inserted into the special iron pipe (3), the spring (12) causes the inner rod (11) to extend out of the sleeve (6) near the carbon brick (9). After the sleeve (6) is inserted into the special iron pipe (3), one end of the inner rod (11) first contacts the side wall of the carbon brick (9), and then the sleeve (6) continues to be inserted until the end contacts the side wall of the carbon brick (9). At this time, the spring (12) is compressed and the mark at the other end of the inner rod (11) extends out of the inner wall of the sleeve (6).

5. A device for online prediction of hearth wall thickness EMF at the end of blast furnace service according to claim 1, characterized in that, The sleeve (6) is made of high temperature resistant material.

6. A device for online prediction of hearth wall thickness EMF at the end of blast furnace service according to claim 4, characterized in that, The inner rod (11) has three parts.

7. A device for online prediction of hearth wall thickness EMF at the end of blast furnace service according to claim 1, characterized in that, The special iron pipe (3) has an external thread at its end, and the nut cap (2) is fitted on the outside of the end of the special iron pipe (3) and fixed by the thread.

8. A method of using an online EMF prediction device for hearth wall thickness at the end of a blast furnace service life, comprising using the online EMF prediction device for hearth wall thickness at the end of a blast furnace service life as described in any one of claims 1-7, characterized in that... Includes the following steps: Select the grouting hole on the furnace shell (4) and remove the original filling material from the grouting hole and clean it until the hole wall is solid and clean; The special iron pipe (3) is welded and fixed to the furnace shell (4), and the special iron pipe (3) is coaxial with the grouting hole; Insert the sleeve (6) into the grouting hole until the end of the sleeve (6) contacts the wall of the carbon brick (9); Determine the insertion depth of each EMF probe (1), insert the EMF probe (1) into the sleeve (6), and fill the sleeve (6) and the gap between the sleeve (6) and the carbon brick (9) with carbon ramming material (7) to fix the sleeve (6) and the carbon brick (9) and fix the EMF probe (1) and the sleeve (6); The EMF probe (1) is fixed to the nut cap (2), and the nut cap (2) is fixed to the special iron pipe (3); After the EMF probe (1) is installed, the furnace wall thickness is calculated using the following formula: ； Where E(δ) is the electromotive force measured in the hearth, δ is the hearth wall thickness, S is the Seebeck coefficient, q is the heat flux density, and λ is the thermal conductivity of the material.

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